The Oakland man who was the focus of a police investigation into the disappearance last year of his missing 21-month-old daughter has been found dead, authorities said Monday.

The body of John Anthony Webb, 50, was discovered at his Oakland home on Friday. The cause of death is under investigation, but the Alameda County coroner's office said it did not appear to be the result of foul play.

Webb had reported July 10, 2013, that his daughter, Daphne Viola Webb, had been kidnapped from outside an East Oakland market. Despite numerous searches and an intense police and FBI investigation that focused on Webb, the girl hasn't been found.

Webb was briefly jailed on suspicion of child endangerment based on his statement to police that he had left Daphne in his Ford Expedition with his 87-year-old mother, who suffers from dementia. Webb said he had stopped to get an energy drink at Gazzali's market at 79th Avenue and International Boulevard in East Oakland.

Alameda County prosecutors declined to file charges, and Webb was released from jail. But police had asked the public and other law-enforcement agencies to report any sightings of Webb - with or without Daphne - in the weeks before she disappeared. Investigators also wanted to know about any "hits" of his Ford Expedition on automatic license plate readers.

They have been joined at vigils by Mark Klaas, the father of murder victim Polly Klaas.

"In my mind, there's little to no doubt that he is responsible for that action, the disappearance of baby Daphne," Klaas said Monday. "It looks like he's going to take that secret to the grave, and the family will never have closure and will never know what happened to their child, which of course is very terrible and unfortunate."

The case has drawn comparisons to that of Hasanni Campbell, a 6-year-old Fremont boy with cerebral palsy who disappeared in 2009. Hasanni's foster parent, Louis Ross, said the boy was snatched from his BMW as he parked near his fiancee's shoe store in Oakland's Rockridge neighborhood.

But police later said they believe the boy was never in the car and never made it to Oakland. Ross and his fiancee were briefly jailed but were released without charges being filed. The boy is still missing.